There are several possible answers, neither of which have internal support from, nor overtly contradict the MT: 1. The law dates from the time of, or only refers to, the stationary central sanctuary in Bet El or Jerusalem. 2. The law applied only when the altar in the desert was actually set up, not to the time during which it was transported. 3. The law was interpreted to mean "every day" in the sense of at least part of the day and the fire should not be intentionally put out. 4. There was an additional means, possibly miraculous, not mentioned in the text, by which the fire on the altar was transported. The earliest reference to this question is in the [Jerusalem Talmud][1], tractate Yoma (Yom Kippur) Chapter 4, Mishna 6 (page 23b)<sup>1</sup>: > Rabbi Yohanan said "Even during transport the fire was not allowed to go out". What did they do? During transport they covered the fire with a copper hood [loan word from the Greek ψυκτήρ] as Rabbi Yehudah said. Rabbi Shimon said, "During transport they tended the fire [in a separate vessel, not on the altar itself]". Similar problems with other "eternal" commandments occur in the case of the [showbread][2] and its accompanying spice offering, which were solved in practice during the second temple period by either interpreting the commandment to mean "daily" as in (3) above or by sliding off the past week's bread while simultaneously sliding on the new bread.. Note that this problem either did not bother anyone in the ancient world very much, or else the material relating to it was lost in the processes of "natural selection" that favors preservation of texts with more practical value. The Jerusalem Talmud is the only ancient reference and it is a work of secondary importance in the Jewish tradition. Critical scholars today would probably say that Leviticus 6 referred to the stationary sanctuary only, as in (1) above. ----- 1. מתניתא מסייעא ליה לרבי יוחנן לא תכבה אף במסעות, בשעת מסעות מה היו עושין לה, היו כופין עליה פסכתר, דברי רבי יהודה, רבי שמעון אומר אף בשעת מסעות היו מדשנין אותה [1]: https://en.wikipedia.org/wiki/Jerusalem_Talmud [2]: https://en.wikipedia.org/wiki/Showbread